Oil on windscreen

[xrs135]

Over the last 10 hours or so, I've noticed that i've started getting a SUPER fine (what I assume is oil) mist on my windscreen. It's barely noticeable  - you have to look carefully in the correct lighting.

 

Anyway, I've been monitoring it and oil consumption is negligible - right at the usual 1qt ever 10hrs so I haven't been too concerned.

 

When looking around the outer cowling there isn't any noticeable oil. I did notice some very light streaking on the back side of the propeller roots. With the way oil gets everywhere, I can only assume that it's just a few drops of oil at most. Naturally, my first thought was that I am starting to get a leaky prob hub, would need a reseal, etc.  Then, after researching a little bit online, I decided it could possibly just be the $3 o-ring that isn't sealing quite right.

 

After talking to a prop-shop on the phone, I was advised that it likely isn't my prop at all (or at least it would be very strange) since my prop and hub are new with only 150hrs on them.

 

This started to get me thinking... This all started after I did my last oil change. I'll be honest, I didn't do the greatest job at NOT making a mess. I let my (hot) oil drain overnight, hoping that most of it would drain out of the filter. Well, it did not. And I ended up with oil all over the back of the engine compartment and down onto the nose wheel. After I finished the oil change, I wiped down the engine compartment and nose wheel with some rags as best I could... But I wasn't able to spray it down with mineral spirits like most shops do.

 

Could this be the source of my problem? ...Leftover drops of oil in the engine compartment, getting pushed up out through the engine compartment due to turbulent air flow... and then getting flung by the prop and onto my windscreen? 

 

Also, is there anything else that I could use to better clean out my engine compartment since I don't have compressed air/mineral spirits readily available?

 

I figure this is the cheapest/easiest fix to my problem. Next step would be to just leak-check the entire engine if it's till flinging oil, and finally, if those two things don't work, THEN start troubleshooting the crank/prop seals.

 

Thoughts?

 

**Sidenote: After that first oil change, I immediately bought one of those fold-a-funnel things so hopefully the next one goes smoother!

[kortopates]

Certainly not from a messy oil change, that oil would go out the bottom - not the top. It would have to be from the prop or crankcase seal. When the oil mist is on the face of the propeller its more likely the prop. Pull the spinner and look inside that as well as the blade roots and look at the crankcase seal area. Be careful to put the spinner back on the same orientation it came off to not upset the balance.

[OR75]

Propeller overhaul or reseal in the horizon

[Delta]

I would not dismiss the oil mess as the cause. Try to wipe clean a much spilled oil as possible, especially around the nose gear area.

[Guest]

Start with the simple and work to the difficult. Buy yourself a one gallon weed sprayer at Walmart and some Carson or mineral spirits. Remove the cowls and wash your engine clean, don't spray your vacuum pump wrap it with at plastic bag. Removed and wash the prop,spinner and prop as well as the engine cowls. Re install everything and do a ground run, open the cowls and look for signs of the leak, if nothing install cowls and to a very short flight, land and open cowls look for the leak.

Clarence

[Shadrach]

Clarence gives sound advice above. If it is oil and not grease, it's unlikely to have anything to do with a Hartzel prop. If it was oil coming from a McCauley, it would likely be red.

It is unlikely that it came from a messy oil change, however oil can do odd things in the turbulent airflow of a Mooney cowl. A lot of the air the enters the cowling spills right back out the front. It takes very little oil to make a huge mess. I would bet the source of the oil is the crank seal. Easy fix.

[Mike A]

Start with the simple and work to the difficult. Buy yourself a one gallon weed sprayer at Walmart and some Carson or mineral spirits. Remove the cowls and wash your engine clean, don't spray your vacuum pump wrap it with at plastic bag. Removed and wash the prop,spinner and prop as well as the engine cowls. Re install everything and do a ground run, open the cowls and look for signs of the leak, if nothing install cowls and to a very short flight, land and open cowls look for the leak.

Clarence

 

Just for general engine cleaning practice information, do you wash off the mineral spirits with water after application?

[Andy95W]

Just for general engine cleaning practice information, do you wash off the mineral spirits with water after application?

No, it evaporates off. Takes a few hours, or just run the engine for a bit.

[carl]

And what is Carson ?

carl

[robert7467]

I used AVGAS for cleaning my engine. The seals in the sprayer will rot out, but its quick.Clean the engine off real good and let it run at idle for a few mins. If you run it at a higher RPM it will blow the oil everywhere and make it harder to find.

 

Check around all bolt holes around the crank case, check all the oil return tubes (also make sure the return tubes are not rubbing against the baffling).

 

I have been chasing oil leaks ever since I owned my Mooney (around 4 years) and here is what I found:

 

Oil return tube rubbed against baffling causing a pinhole. I brazed tube and its fine.

The oil pan bolts on the back of the oil pan were loose (towards the firewall). Those were a real pain to tighten. It took flexible socket extensions, swivels and had to keep probing until it caught the bolt because you cant see back there.

 

Just take your time and get several sets of eyes on it with a bright flashlight.

 

Also, the pinhole leak on the return tube was not that bad for around 50 or so hours, then on the ground it started spewing out oil everywhere and thats how I was able to find it. if I was 5 minutes up in the air with that leak, it would have ended up a disaster.

[DAVIDWH]

A few years ago we got a DC-6 washed with gasoline in Haiti.

 

Came out sparkling, unable in Miami. Some FAA thing.

 

Just a recc. if you are looking for a really clean engine.

 

Best,

 

Dave

[N33GG]

You can cover an entire airplane with a teaspoon of oil.  If you are seeing any oil on the prop, I would be very suspicious, regardless of how recent overhaul was and how unlikely it is.  Clean the prop, and watch for more oil.  It won't be much, but a little tiny bit leaking will easily show up on the windscreen. 

 

Next choice, as mentioned above, is front crankcase seal.  If I were betting, and I never bet, my money would be on the prop. 

 

Good luck.

[xrs135]

Thanks for all the input guys! I can probably manage to clean the engine up with the mineral spirits and pump up sprayer... but I will leave removing the prop and cleaning it to the mechanics - that makes me too nervous doing that.

Sounds like I good cleaning/leak check... And then If I have no luck, new crank and prop seals and it should hopefully resolved.

Any idea how big of of job and how expensive it would be to change out both those seals?

[robert7467]

If you are looking for something less volatile than avgas, then you can get a gallon drum of kerosene from Lowes, or you can also use Jet A. It takes a while to dry though.

[Shadrach]

Do you have a hartzell or a McCauley?

 

Are there grease streaks on the face (back) of the prop working there way out?

 

Oil is usually from the engine, not the prop unless it is red in color.  If you have brown oil coming from a Hartzell prop, do not even start the engine again as something has failed so miserably that you have big problems... 

 

Do make sure the governor like is properly torqued.

 

Minor outward streaking on the spinner backplate is normal. 

[MyNameIsNobody]

I had that and it grew to misting windscreen in a two-hour flight. Not a big oil loss, but was a safety of flight issue. After two prop seals learned that the case halves had separated...Overhaul soon followed. First for that engine.

[xrs135]

Do you have a hartzell or a McCauley?

 

Are there grease streaks on the face (back) of the prop working there way out?

 

Oil is usually from the engine, not the prop unless it is red in color.  If you have brown oil coming from a Hartzell prop, do not even start the engine again as something has failed so miserably that you have big problems... 

 

Do make sure the governor like is properly torqued.

 

Minor outward streaking on the spinner backplate is normal. 

I have the Hartzell Scimitar prop. There are very slight streaks on the back (black side) of the propeller root - extending maybe 4 inches. I can't tell if it's oil or grease, because I can't even tell what color it is... but it definitely seems 'oily'

[ryoder]

Can you clean the engine with brake parts cleaner?

 

[Guest]

A few years ago we got a DC-6 washed with gasoline in Haiti.

 

Came out sparkling, unable in Miami. Some FAA thing.

 

Just a recc. if you are looking for a really clean engine.

 

Best,

 

Dave

100LL is a great cleaner and dries instantly.  Be very cautious it's very dangerous.

Clarence

[xrs135]

Can you clean the engine with brake parts cleaner?

 

I remember a mechanic saying something about that once. Brake parts cleaner from NAPA or something like that...

[Bob_Belville]

The A&P/IA who did all my maintenance on my first M20E started the annual by removing the cowling and spraying everything with GUNK. As I recall he used 2 cans.

[DaV8or]

My airplane has stigmata. I too have oil mist on the windshield and I know where it comes from. It comes from a rivet on my upper cowling just aft of the prop and on the right side above cylinder #1.

Here's where it gets weird...

When you take the cowling off and flip it over, it's bone dry. Inspection of my prop hub always reveals it to be dry. The same is true for my front crank seal. No oil in places you would expect.

Where I do have a known leak is the number 2 cylinder base gasket. It obviously blows out on the top towards the prop. This has to be where my windshield oil is coming from, but the real mystery is how does it get from the base of number 2, to the rivet above number 1 without a trace???

It is an annoyance and that's all. The amount of oil loss isn't even easily measured. To me, its not worth pulling the jug for. I have come to accept that my airplane weeps due to my ham fisted flying, bone head flying skills. To which I tell her- "Suck it up Buttercup!! I pay the bills around here!!"

[Andy95W]

Dave-

If you have a rivet that looks like dark oil is leaking out of it, but the inside of the cowling is dry, it is probably a "smoking" rivet that is exhibiting fretting and leaving aluminum oxide dust in the aerodynamic slipstream. 

Google "smoking rivet" and go to images to see if yours looks like the pictures.

[DaV8or]

Dave-

If you have a rivet that looks like dark oil is leaking out of it, but the inside of the cowling is dry, it is probably a "smoking" rivet that is exhibiting fretting and leaving aluminum oxide dust in the aerodynamic slipstream. 

Google "smoking rivet" and go to images to see if yours looks like the pictures.

Nope. It leaves a streak of recognizable oil behind it directly in front of the spray on the windscreen. The streaks are darkened though by the "smoking" effect.

[Andy95W]

Nope. It leaves a streak of recognizable oil behind it directly in front of the spray on the windscreen. The streaks are darkened though by the "smoking" effect.

well, call me baffled...